The present invention relates in general to core-shell materials. More particularly, it relates to core-shell structures with magnetic, thermal, and optical characteristics and manufacturing methods thereof.
Metal nanoshells are a novel type of composite nanoparticle consisting of a dielectric core such as silica covered by a thin metallic shell such as gold. Nanoshells possess highly favorable optical properties for optical imaging of tissue. The optical absorption of the gold shell includes the near-infrared (NIR) wavelength region (650˜900 nm), a region of high-physiological transmissivity, which allows the NIR to be used as an excited source of gold nanoshells to identify tissue.
On the other hand, superparamagnetic nanoparticles are of intense interest, magnetizing strongly under an applied flied, but retaining no permanent magnetism once the field is removed. The on/off magnetic switching behavior is a particular advantage in magnetic-related applications. However, superparamagnetic nanoparticles are usually formed in organic solution or hydrophobic micelle, and thus prone to aggregation or precipitation when entering into body. Furthermore, superparamagnetic nanoparticles are hard to modify, and the diameter is too large for application in biomedicine.
At present, research and development of nanoshells are focused on the optical properties of the metal shell, while that of superparamagnetic nanoparticles are confined to magnetic-related applications. The present invention hereby provides a core-shell structure combining magnetic, thermal, and optical characteristics.